Superheater elements with groups of trifurcated tubes



1950 A. P. J. HUET 2,517,489

SUPERHEATER ELEMENTS WITH GROUPS OF TRIFURCATED TUBES Filed Aug. 22, 1947 ANDRE H06 7' mve/vrae BY MW Patented Aug. 1, 1950 SUPERHEATER ELEMENTS WITH GROUPS OF TRI FURCATED TUBES Andr Philippe Jean Huet, Paris, France, assignor to Combustion Engineering-Superheater, Inc., a. corporation of Delaware Application'August 22, 1947, Serial No. 770,047

In France Junell, 1946 i Sectionl, Public Law 690, Auguste, 194a Patent expires June '11, 1966 The present invention relates to an improved method of integrally joining a plurality of tubes to form a superheater element or thelike.

The joining at the fire box end of the --tubes of a superheater element having multiple tubes presents difiiculties of accomplishment particularly if the superheater element comprises a relatively high number of tubes, for example, four admission tubes for saturated steam and a return flow tube for superheated steam.

The present invention has for an object the simplification of known methods joining such tubes.

According to the invention, a superheater in cluding four admission tubes and a single centrally located return flow tube has a junction at the fire box end made up of an ordinary breeches piece joining three tubes two of which are steam admission tubes and the third centrally located tube is of short length and fits into the open end of a breeches piece joining three additional flow tubes of which two also are steam admission tubes and the third of central tube is of larger diameter and constitutes the return tube of the superheater element.

The invention will be best understood upon consideration of the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings in which:

Figure 1 is a perspective view of the fire box end of a superheater element formed by the joining of a number of tubes in accordance with the present invention;

Figure 2 is a longtiudinal sectional view through the fire box end of a superheater tube shown in Figure 1;

Figures 3 and 4 are transverse sectional views on the correspondingly designated section lines in Figure 2;

Figure 5 is a longitudinal sectional view taken at right angles to Figure 2;

Figure 6 is a transverse sectional view on the line 6-6 in Figure 5; and

Figure 7 is a fragmentary view similar to Figure 5 illustrating a variation of the arrangement illustrated in Figure 5.

As seen in Figure 1 the superheater element shown presents the problem of joining the four peripherally disposed admission tubes II], II, l2 and 13 of the superheater element with the centrally located return flow tube [4. According to the invention two diametrically opposed tubes I and I3 are forge welded together in known manner as part of a forging l joining three tubes 3 Claims. (01. 257-248) of which the central tube It is of shorter length. The open end forging or breeches piece l5 is arched over and closed at IT to form a return bend through which fluidfrom the tubes [0, I3 flows into the tube [6.

'The other two diametrically positioned tubes H and 12 located in a plane at to the tubes ID and I3 are joined together by means of an open breeches piece l8 which also connects them with the return flow tube M which occupies the central position in the superheater element. To complete the assemblage of the superheater element the central tube lb of the first trifurcated member has its truncated tube end It inserted into the rounded and swaged down open. end of the breeches piece 18 that joins together the three tubes l I, I2 and 14 as is shown in Figures 2 and 5.

The dimensions and shape of the truncated tube 16 are calculated in such fashion that the steam flowing through it in the direction of the arrow A induces the entrainment of steam flowing towards the fire box end of the element through the admission tubes H, 12 as indicated by the arrows B and directs all the currents of steam into the central return fiow tube l4 as indicated by the arrow C1 As shown the truncated tube l6 projects into the breeches piece [8 with its end 20 close in the return fiow tube It.

I'he extremities of the truncate or stub tube [6 can, as is seen in Figure '7 be slightly tapered at 2! in such fashion as to assure an injector effect which facilitates the passage of the total volume of steam coming from the admission tubes II), ll, 12 and I3 into the central return flow tube [4 as indicated at 20.

Further the breeches piece l8 can be partly arched over and a lip 24 turned inwardly as indicated in Figure 7 so as to form interior surfaces 23 directing the streams of fluid from tubes H, I2 around the bend into the tube I 4.

One of the advantages of the method described is its easeof accomplishment deriving from the fact that breeches pieces and return bends made up of three tubes are easier to forge than bends with five tubes. A second advantage is that the encumbrance of the flue presented by the assemblage of tubes at the fire box end is reduced as may be noted in Figures 5 and '7.

The invention can be extended to the cases where one desires to join a larger number of admission tubes with one or several return tubes. It suffices for this to engage the central tube 4 of the breeches piece made up of the tubes ll, [4 and I2 into the open end of another breeches piece joining two tubes with a third tube centrally located between them. In the case of three breeches pieces the junctions of the sets of three tubs instead of being offset by 90 as in the exemplification shown in the drawings, shall be spaced by '60. The same disposition can be adopted in the case of a larger number of tubes with supplementary breeches pieces. It is to be noted then that the admission tubes debouch at different points along the flue into the central tube for return flow; the diameter of this central I return tube increases preferably at or near the place of junction and in proportion to the admission tubes that debouch into it.

What I claim is:

1. A multi-tube superheater element comprising a first pair of steam admission tubes extending parallel to and located at diametrically opposite sides of a return flow tube to which they are joined by an open-ended breeches piece; a second pair of steam admission tubes extending parallel to said return flow tube located at opposite sides of said return flow tube in a plane at right angles to said first pair of admission tubes; and a stub tube joined at one end to said second pair of admission tubes by a breeches piece closed to form a return bend with said stub tube extending into the open end of the breeches piece joining said first pair of admission tubes in alinement with said return flow tube.

2. A method of assembling tubes of amultiple superheater element which consists in joining two full length admission tubes with one end of a centrally disposed relatively short section of the return tube by means of an ordinary forged return bend of the trifurcate type, joining into an open lbreeches piece two othenadmission tubes-with the remaining relatively longer section of the main centrally located return flow tube, and introducing the free end of said short section into the opening of the said breeches piece with said first two admission tubes disposed in a plane at right angles to that containing said two other admission tubes to complete assemblage of all the tubes into a superheater element having a plurality of admission tubes spaced about a single centrally located return tube.

3. A :superheater element as recited in claim 1 wherein .a frusto-conical extremity is formed on the end of the stub tube in alinement with the return flow tube so as to assure an injector efiect of steaminto the central return flow tube.

ANDRE: PHILIPPE JEAN HUET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,24Q,3'72 Huet Apr. 29, 1941 FOREIGN PATENTS Number Country Date 402,457 Great Britain Dec. 4, 1933 

